


wish we could turn back time (to the good old days)

by mainstreamelectricalparade



Series: Hardest Lessons (Softest Results) [11]
Category: Marvel Cinematic Universe, Spider-Man (Tom Holland Movies)
Genre: Age Regression/De-Aging, Fake Science, Fluff, Gen, Humor, Kid Fic, Kid Peter Parker, Medical Inaccuracies, Nostalgia, Other Additional Tags to Be Added, Parent Tony Stark, Peter Parker is Tony Stark's Biological Child, Precious Peter Parker, like barely on both of those but i feel it necessary to tag
Language: English
Status: In-Progress
Published: 2020-08-10
Updated: 2020-08-20
Packaged: 2021-03-06 07:42:13
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 7,499
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25819783
Author URL: https://archiveofourown.org/users/mainstreamelectricalparade/pseuds/mainstreamelectricalparade
Summary: Peter was so absorbed in the treasure trove of memories that he didn't hear the lab doors open, didn't hear footsteps approaching until they were right behind him. He nearly startled, but was quick to recognize his father's heartbeat, and the smell of coffee and motor oil, relaxing even before he felt Tony put his hand on his shoulder."So this is why I haven't seen you all day," Tony teased, looking over Peter's shoulder at the video on the computer screen; nothing particularly exciting, just Tony and one year old Peter sitting on the floor building a block tower, having one of those conversations that made absolutely no sense but Tony obviously treasured anyway. "You found the baby videos."
Relationships: Peter Parker & Tony Stark
Series: Hardest Lessons (Softest Results) [11]
Series URL: https://archiveofourown.org/series/1186103
Comments: 101
Kudos: 411





	1. Chapter 1

**Author's Note:**

> me: i've been writing a lot lately i think it's time for a break  
> peter's birthday: hi  
> me: .......... time to start a multichapter fic based on a vague idea with no semblance of an outline whatsoever except for a possibility of an idea for an ending
> 
> ok so i know the de-aging thing has kind of been done to death but i haven't seen many (if any at all) where peter is tony's biological son, so they've technically already been through all this before, so it's less panicked flailing and just reliving fond memories/figuring out ways to make new ones. i'm not entirely sure where i'm going to go with this, but i hope you enjoy it!

"Hey, FRIDAY." Peter asked, bursting into the lab one evening with his backpack slung over his shoulder, heading straight for his homework desk and flopping into his chair. "Need help with an assignment."

 _"Certainly, Peter,"_ FRIDAY agreed pleasantly. _"What do you need help with?"_

"Baby pictures," Peter replied, booting up his computer and grabbing his social studies notebook out of his backpack. "I know my dad has like a million, so I just need to find the least embarrassing one for a project."

 _"Luckily for you, Boss keeps all his files pertaining to you sorted very carefully,"_ FRIDAY said, taking Peter straight to a file labeled _Peter - 2001-2003_. There were several sub-folders within it, meticulously labeled. _"You should find everything you need right here."_

"Awesome," Peter said gratefully. Honestly, finding the right file in his dad's crazy organizing system would have been 75% of the challenge, without FRIDAY's help, so this was going to be a piece of cake, now. He scanned through the list of sub-folders to find the photos. "Let's see, medical records... Baby monitor, haha... milestones... jeez, he tracked everything, huh? Videos... oh, there we go, photos!" Peter hovered the mouse over the "photos" folder, then paused, looking back at the previous one.

Videos? Had Tony somehow mislabeled baby monitor footage, or something? Curiously, Peter clicked on the folder, and immediately his screen was filled with hundreds of video thumbnails, each labeled with a date and timestamp to indicate when it had been taken. One of the first was labeled _20010820_2135_. Ten days after Peter had been born. He must have been barely out of the NICU, then.

Peter clicked on the video. It was nighttime, the room on the screen lit only by a single bedside lamp. He recognized the master bedroom of the old New York penthouse they used to have before they moved into the Tower, the only difference to what he remembered being a portable baby cot in the corner of the room.

Tony stood in the middle of the room, fifteen years younger, with a much darker head of hair and a tiny, softly fussing baby in his arms. He looked tired, a little frazzled maybe, but when he turned to face the camera he had a gentle look on his face as he soothed the wiggly little bundle, murmuring to him softly. The video's audio wasn't very loud at all, but Peter could make out his dad's voice, soft as ever, saying, _"Dad's here, Pete, you're ok, I've got you. Go back to sleep, buddy, I can see you fighting it."_

He couldn't help smiling as he heard the words, because even now they were _so familiar_. He was fifteen now, and too big to carry around like that, but even so, whenever he had a bad night, his dad was right there to say, _"I'm here, it's going to be ok. Go to sleep."_

Apparently in the video, baby Peter had finally fallen asleep, because Tony stopped pacing in circles and paused in the middle of the room, staring down at the sleeping baby like he was holding the entire universe in his arms. _"There you go,"_ he whispered, shifting Peter in his arms so he could kiss his forehead before stepping closer to the portable cot and gently setting him down in it. _"Good night, little man."_

The video clip ended, and Peter sat back in his seat, a small lump starting to form in his throat.

 _"Are you alright, Peter?"_ FRIDAY asked, her volume a little quieter and her tone more gentle than it had been before.

Peter cleared his throat a couple times, though the lump was rather persistent, it seemed. "Yeah, I'm ok," he nodded, his eyes scanning over the hundreds of other video files that were undoubtedly just like the one he had just watched.

He clicked another one.

* * *

_**November 2001** _

_The video was a slightly lower quality, taken with a handheld camcorder, which was trained on three month old Peter as he lay on his back on the floor of the living room, naked except for a diaper, and looking very happy about it. Tony's hand was in frame, one finger being gripped by Peter's entire tiny hand, but that was all that could be seen of him._

_"This little man," Tony announced from behind the camera, and on the floor Peter started to wriggle excitedly at the sound of his daddy's voice, cooing and gurgling, "just had a bath. He did not enjoy it, and he also did not enjoy it when I tried to put clothes on him after the fact. He's extremely ridiculous." _

_Peter broke into a big, gummy grin, wiggling in earnest now, his breath coming in little huffs like he was trying to laugh. "Yeah, you, mister," Tony agreed, his voice sliding into a softer tone that sounded a little more like cooing, gently extracting his finger from Peter's grip so he could rub the baby's bare tummy. "You're ridiculous. You're itty bitty, you're gonna get cold, and then you'll be mad at me anyway. But this is what we're working with right now."_

_Peter cooed, and Tony's hand reached up to run over his fuzzy, freshly-washed hair. "Yeah, I know. I love you too, bambi." Peter blew a spit bubble, and Tony laughed. "Alright, I'm turning off the camera now. Just had to record this. Happens almost every night, it's pretty much part of the routine now. He'll probably get cold in about five minutes, and start screaming at me, and I'm going to tell him 'I told you so', and then I am going to put a onesie on him, whether he likes it or not, and then we'll probably spend an hour or so in the rocking chair until he passes out." Tony's finger stroked Peter's cheek gently, eliciting another gummy smile from the already very happy baby. "Say good night, Peter Pan."_

_Another spit bubble, another fond chuckle, and the video cut off._

* * *

_**March 2002** _

_Peter's nursery, a few months later. The camera angle was from one of JARVIS's security cameras, though it was zoomed in and focused on Tony and Peter as they sat in the rocking chair next to Peter's crib. A humidifier sat nearby, humming softly as it emitted a steady stream of thin, swirling steam. Tony was fully relaxed into the seat, slouching a little to create a comfortable reclined backrest for Peter, who was laying against his chest, eyes half-closed and fluttering, three tiny fingers wedged in his mouth. He was obviously trying his best to fight sleep as Tony read to him in a quiet, soothing voice, one foot pushing against the floor to keep up a slow rocking motion, face turned towards Peter, his lips brushing against the top of his fuzzy head with every murmured word._

_"Goodnight nobody / Goodnight mush / And goodnight to the old lady / whispering 'hush' / Goodnight stars / Goodnight air / Goodnight noises everywhere."_

_Tony lowered the book and tilted his head to see if Peter was asleep yet, and Peter blinked big brown eyes right back up at him. Tony sighed softly, kissing his temple._

_"You gotta go to sleep, sweetheart," he whispered. "Alright? You can breathe better now, yeah, so why won't you let me put you down?"_

_As if he understood the question and wasn't a fan of the implications behind it, Peter let out a soft coo of dismay, taking his fingers out of his mouth to make a sleepy grabby-hand at Tony._

_Tony rubbed his belly soothingly, reassuring him that he wasn't doing anything of the sort, yet. "I know, peanut, I'm still here, don't worry. Just feeling clingy tonight, huh?" He carefully turned Peter over so that they were chest to chest, and Peter immediately curled up and nestled into his favorite spot, his face tucked safely into his daddy's neck. Tony smoothed big, slow circles into his baby's back, keeping up the gentle rocking. The look on his face suggested that he knew he wasn't going anywhere, tonight, and he was perfectly fine with that. "Go to sleep, lovebug. Daddy's here."_

* * *

_**August 2002** _

_Tony's home office. Tony had the camera propped up on his desk, pointed at the swiveling office chair, which he sat down in with Peter in his lap within seconds of the video starting._

_"Had to turn the camera on, 'cause this is too cute not to film," Tony said, looking down at the little boy in his lap with that achingly fond look on his face, offering his child all the love in the universe with one gesture. Peter tilted his head back to look back at Tony, and giggled, amused by seemingly nothing, reaching up to pat his daddy's face clumsily. Tony kissed the tiny fingers when they bumped over his mouth, then lifted Peter slightly to rearrange him in his lap, so that he faced the camera a little more._

_"This is kind of a fun new development: Peter loves swivel chairs," Tony continued, explaining his reasoning for turning the camera on. He dropped a kiss on top of Peter's head, then reached for his little hands, allowing Peter to grip his fingers tightly for balance as he started to rotate the chair back and forth._

_As soon as the motion started, Peter's face lit up, and he giggled wildly, bouncing in Tony's lap and enjoying the ride with a big, half-toothy grin on his face. "Dahey!" he squealed, delighted._

_"Petey," Tony cooed back, leaning around to see the look on Peter's face and smiling widely. "That fun?"_

_Peter wriggled with excitement, huffing with laughter as he looked back at his daddy, before he started attempting to turn around in Tony's lap. Tony slowed the spinning a little and let go of Peter's hands so he could hold on to his chubby little waist and steady him as Peter grabbed on to the front of his shirt and attempted to pull himself up to stand in his lap. With Tony holding him tight so he didn't topple onto the floor, he flung his chubby little arms around his daddy's neck and lurched forward to press a big, slobbery kiss to his stubbly cheek. "Dahey," he cooed. "Wuv Dahey."_

_The chair's side to side motions slowed to a complete stop as Tony leaned back to look at Peter properly, visibly overcome with emotion at the declaration. He reached up and ran his hand through Peter's sparse curls, pressing their foreheads together and closing his eyes. Peter's eyes fluttered closed as well, little hands patting Tony's cheeks as he babbled softly._

_"I love you too, sweet boy," Tony murmured, just loud enough for the camera's microphone to pick up. "More than you'll ever know."_

* * *

_**October 2002** _

_"Guess who's getting glasses today," Tony said from behind the camera, which was pointed at Peter, sitting in his car seat in the back of the car. They were outside, already at their destination, with the back door swung open so that Tony could film. "You ready, big guy? Gonna finally be able to actually see shapes now, and not just big blobs, because you-" he reached into the car to poke Peter's belly through the straps of his car seat, "-are legally blind. Yes, you are. No wonder, huh? Clumsy little dude."_

_Peter giggled, leaning half out of his car seat with both arms outstretched when Tony withdrew his hand, trying to reach his daddy. "Dahey, up!" he chirped. "Peas!"_

_Tony laughed, and the video cut out, but only for a moment, before switching to a new setting, this time inside the fitting area of an eye doctor's office. Peter was settled in a booster seat, his eyes trained on Tony, who was still holding the camera, while a doctor wearing a white coat stood beside him, fiddling with a tiny pair of glasses, making sure the ear pieces and the band that went around the back to keep them from falling off were adjusted properly._

_"Alright, here we go," the doctor said, turning to face Peter fully, showing him the glasses so he didn't startle him by putting them on without warning. That didn't stop Peter from making quiet sounds of displeasure as the foreign object was fitted over his head and slipped down past his forehead to sit on his nose, but he didn't throw a tantrum._

_The doctor moved his hands away to let Peter adjust to his new vision, and the camera zoomed in on Peter's face as his big brown eyes, magnified slightly by the new lenses, went wide with shock as he started to take in his surroundings with a whole new light._

_"What do you think, Pete?" Tony asked from behind the camera, his voice fond as he watched Peter look at the brand-new 1080p world he finally had access to. Peter's eyes snapped up to look at Tony again at the sound of the familiar voice, and his eyes went impossibly wider, his mouth falling slightly ajar. He lifted a little hand up to make a grabby hand._

_"What, honey?" Tony said softly, the camera angle shifting as Tony crouched down in front of Peter's chair and took his hand._

_Peter leaned forward, his face getting close enough to the camera lens that the focus blurred as his little hands reached out to pat his daddy's face. The angle shifted again as Tony ducked his hand under Peter's arm and held the camera slightly out of the way; Peter was no longer directly in the shot, but there was a mirror that the camera was pointed at instead, which showed Peter and Tony both._

_"Dahey," Peter murmured, patting his little hands all over every inch of Tony's face, which he could now see with perfect clarity._

_Tony's face softened. "Yeah," he murmured back, rubbing Peter's knee with his thumb. "Can you see Daddy now, Petey?"_

_Peter nodded, then his lower lip popped out in a wobbly pout and he whined, " Dahey."_

_The camera caught Tony's expression in the mirror, melting into one of overwhelming love before the lens ended up pointed at the floor, jostling slightly. There was brief audio of Tony cooing, "Oh, baby boy-" before the video cut off._

* * *

Hours later, Peter was still sitting at his desk watching those old home movies, his chin propped in his hand with his elbow resting on the desk.

Some clips were very short, where Tony turned the camera on only long enough to capture a few precious moments of time to immortalize them; one month old Peter who had just learned that he had facial muscles, and had his face screwed up in a funny little scowl with his tongue poking out between his lips while Tony snickered and whispered, _"What the hell, Pete?_ "; two month old Peter sneezing four times in a row, and the video frame shaking as Tony started to laugh; Tony pointing the camera at himself somewhat awkwardly, obviously trying not to wake Peter, who was dozing on his chest, drooling a small river down what looked like a very expensive work shirt.

Others were longer. "Conversations" that Tony held with Peter, lying on the floor across from each other doing tummy time. Peter would babble something nonsensically, or flail his little limbs and let out a piercing squeal, and Tony would respond as if Peter had said one of the most intelligent sentences he'd ever heard. Video taken by Rhodey at the poolside, of Tony reassuring Peter through his first experience with water that wasn't in a bathtub, of Peter screaming bloody murder when his duck floatie drifted too far from his daddy, and calming down when Tony pulled him back, of Tony dripping a little bit of water on Peter's arm and letting him inspect it carefully until he realized that it wasn't going to hurt him. Footage of Tony's birthday when Peter was nine months old, snuggled up in Tony's big bed together sharing a plate of pancakes.

A countless number of videos of nothing but cuddles, in the nursery, on the couch, on the floor, in Tony's home office late at night because Peter was teething and wouldn't sleep unless Tony held him. Tony singing to Peter, either to lull him to sleep or soothe him when he was fussy or in pain, with a wide range of musical genres; Italian lullabies, nursery rhymes, soft rock, and Disney tunes.

Peter was so absorbed in the treasure trove of memories that he didn't hear the lab doors open, didn't hear footsteps approaching until they were right behind him. He nearly startled, but was quick to recognize his father's heartbeat, and the smell of coffee and motor oil, relaxing even before he felt Tony put his hand on his shoulder.

"So this is why I haven't seen you all day," Tony teased, looking over Peter's shoulder at the video on the computer screen; nothing particularly exciting, just Tony and one year old Peter sitting on the floor building a block tower, having one of those conversations that made absolutely no sense but Tony obviously treasured anyway. "You found the baby videos."

"Yeah," Peter said softly, glancing at his dad before returning his attention to the computer screen. "I was looking for photos, for a school assignment, and this folder was right next to it, and I've never seen these before, so..." He shrugged, sniffing once in a way that he hoped could be passed off as "I need to blow my nose" rather than "I've been watching these videos for hours and it's making me kind of want to cry".

Unfortunately, Tony knew him far too well to let him get away with that. He squeezed Peter's shoulder gently, frowning a little as he tilted his head to see Peter's face better. "You ok, kiddie?"

Peter swallowed hard, avoiding meeting Tony's gaze directly so he didn't break down right away. "Yeah, I just kinda... I don't know, watching all these videos... makes me think about stuff."

There was a gentle hand in his hair, now, massaging his curls, wordlessly urging him to keep going. "What kind of stuff?"

Peter sighed, his entire body tilting sideways until he flopped into his dad's chest, tired. "I miss you," he admitted, his voice small, embarrassed to say it because _Tony hadn't gone anywhere_. What was there to miss?

Tony's arms wrapped around Peter, pulling him closer. "I'm right here, buddy," he said softly.

"I know. But..." Peter looked back at the computer screen. The video had ended, and the folder full of video files was on display once more. He gestured with a limp hand. "I miss _that_. When it was just... just you and me, and there weren't any problems, or stupid Avengers, or secret agencies taking up all your time so I barely see you anymore, and when I do you're always tired and frustrated because of whatever meetings you've been in..." He bit his lip and broke off, having said more than he meant to.

Peter closed his eyes and turned to half-hide his face in his dad's chest as he felt a kiss being pressed to the top of his head. Tony's chest rumbled lowly under his ear as he murmured, "I miss it too, bud. Believe me."

"I wish things could go back to how they were. Just for a little while. I feel so selfish, because everything you're doing is _so important_ , and it's amazing, but..." Tears pricked the corners of Peter's eyes and he pressed himself closer to Tony. "I miss my dad."

"Aw, Pete..." His dad's strong arms tightened around him, holding him in a protective embrace, like that alone could fix everything.

(When Peter was little, it could have.)

Peter huffed in frustration, mostly at himself, reluctantly pulling away from his dad's arms. "Um, is it ok if I go out as Spider-Man for a little while?" he asked, rubbing his arm over his face tiredly. "I'm thinking too much, and it helps me clear my head."

The look on Tony's face suggested he was reluctant to let Peter go out and fight crime if there was even a slight chance he might be distracted, but he sighed, running his hand through Peter's hair once and nodding. "Homework's done, yeah?"

"Yeah, just this project left. Not due for a while."

"Come home if you're too distracted," Tony ordered, allowing Peter to get up and go retrieve his suit from the bio-locked drawer it was tucked away in. "And grab something to eat while you're out, you missed dinner."

"Thanks, Dad."

* * *

Every so often, Spider-Man still came across someone who'd bought a weapon from Toomes before he got arrested. Tonight was one of those nights.

"You know, that's a pretty fancy gun for a simple ATM robbery," Peter pointed out, catching the guy off-guard and making him miss when he tried to shoot at the surveillance camera pointed at the ATM. Oddly enough, the massive purple blast it emitted didn't seem to do much damage; it just bounced off the corner of the brick wall and dissipated. "Nice shot," Peter said dryly.

The guy swore when he realized who had interrupted his attempted felony. "Jesus, I do not need to deal with the Spider twerp tonight," he grumbled, lifting his gun again and pointing it at Peter.

"It's Spider- _Man_ , thanks," Peter corrected, raising his hands as if he was actually planning to comply to whatever this guy was going to try to tell him. "So, here's a thought, how about you put the gun down, so I can add it to my collection of confiscated alien tech, and never try to rob anything again, and I won't tell anyone about this? Huh?"

"Shut up," the guy muttered, and pressed the trigger. After seeing what the gun did (or rather, didn't do) to the wall, Peter wasn't exactly afraid of it, but he dodged the blast anyway, shooting a web high and jumping up the wall.

"You missed."

_"Shut up."_

Another blast. Another dodge. Peter tumbled to the sidewalk behind the robber, rolling head over heels before catching himself and standing up straight. The robber whipped around and took another shot, and Peter was still recalibrating his sense of "up" and "down", so his attempt to dodge wasn't quite as successful as the first two. The blast smacked him in the stomach, making him stumble back, and on reflex he shot out a web in the robber's general direction. Must have been pure Spidey luck that he hit the gun dead center, giving a sharp tug to yank it out of the guy's hands and sending it clattering to the ground before shooting more webs to incapacitate the guy before taking a step back to assess himself, while the robber swore loudly at him from his new spot lying flat on his back webbed to the sidewalk.

The blast hadn't caused any visible damage, at least not that Peter could see through the suit. There might be a bruise or something that he'd find later, but he didn't feel any great pain. Still, it was alien tech, so even though Peter felt fine now, he knew there was a chance he might not, later.

"Ok, uh, Karen, call the police and tell them to come pick this guy up," Peter suggested, before stepping closer to the fallen gun and picking it up gingerly. "I need to get this to Da-" He stopped himself, glancing back at the robber, who had stopped swearing and was now just glaring at him fiercely. "Mr. Stark."

 _"The police have been notified and will arrive within fifteen minutes,"_ Karen reported after a minute.

"Great, thanks." Peter tucked the gun under his arm, careful not to touch anything that looked like it could be a button, and gave the robber a cheery little salute as he shot a web to swing away. "Later, Mr. Robber Guy! Have fun in jail!"

* * *

_"You what?"_

"Got hit by one of those unholy alien remix weapons, but don't worry! I'm doing fine so far," Peter said quickly, though he had a feeling nothing would reassure his dad that he was fine until he saw for himself and got a medical opinion.

_"Peter-"_

"Like, considering the kind of stuff I've seen these things do in the past, this one seems pretty tame. Dude blasted a wall and didn't even scratch it, and I seriously don't even feel bruised."

_" Peter."_

"I know, I know, I'm coming home, chill," Peter said quickly. "And I'm bringing the thingy with me, so you can put it wherever you're keeping the rest of this stuff."

_"Excuse me mister, you did not just say you got hit with alien tech and then tell me to chill-"_

"Actually, if the court reads the records back, I think you'll find that that's exactly what I said."

_"Don't be a smartass when your father is freaking out, I have a heart condition."_

Peter snorted, rolling his eyes. "Ok, but seriously, chill, I'm literally getting home now, you can commence your in-person freakout in t-minus ten, nine..."

He scaled the side of the Tower quickly and hung up on Tony right as his dad was in the middle of complaining that his count-down had _better be accurate, you little sh-_ and hopped through the open window of the penthouse just in time to see his father coming up the stairs from the lab with a hilarious cross between a scowl and a pout on his face.

"I can not believe you hung up on me," Tony grouched, marching across the living room as Peter pulled his mask off and stood still to resign himself to a quick once-over for injuries. "Who even raised you?" Peter raised an eyebrow and opened his mouth to reply, but Tony cut him off, tweaking his nose gently. "Don't answer that, I _know_ , ok?" Peter snickered and closed his mouth again.

Tony sighed, seemingly satisfied by the lack of immediately visible injuries on Peter's person, patting his shoulder a couple times and then taking the gun from him gingerly, holding it carefully to inspect it. "Well, it sure as hell _looks_ like it packs a punch."

"Yeah, you'd think, but I really don't think that guy got what he hoped he was paying for," Peter agreed. "I feel fine."

Tony looked up from the gun to fix Peter with a suspicious squint. "We'll let Helen be the judge of that," he said sternly, setting the gun aside to deal with later and shooing Peter toward the elevator. "Your idea of _fine_ is three cracked ribs and a stab wound. Med-Bay, now."

"Ok, but that was a _really shallow_ stab wound-"

_"Peter."_

"Med-Bay! Going!"

* * *

"He's fine," Helen announced, looking up from her computer screen, which displayed the results of Peter's full-body scan as well as a list of his vitals. "No bumps, no bruises, nothing broken or fractured, and as far as my scanners can tell, his biology hasn't been tampered with. He's just as healthy as he was this morning."

"I told you," Peter grumbled, tugging a clean Stark Industries-branded shirt on over his head, which Helen had given him after he took his suit off to prove that the impact from the blast hadn't left any nasty bruises anywhere.

"Good," Tony said, letting out a quiet sigh of relief. "Thanks, Cho."

"Anything for my favorite patient," Helen teased, offering Peter a fist bump as he hopped off the exam table. "Let me know if you start feeling anything later, alright? I don't know if this is one of those occasions where the blast has delayed side effects. It's always hard to tell, with alien stuff."

"Ok," Peter agreed, smiling and waving at her as he and Tony headed out the door to take the elevator back up to the penthouse. She waved back, smiling fondly.

"Told you," Peter repeated, as the elevator took them back up to the top floors of the Tower. "Nothing to worry about."

"With you there's always something to worry about, kid," Tony deadpanned, though the arm tossed comfortably around Peter's shoulders suggested he didn't mind as much as he tried to sound like he did. "Comes with the whole _dad_ thing."

"Sounds exhausting."

"Very."

"But you love me anyway." Peter said it with a cheeky grin on his face, expecting Tony to take the bait and tease him back, but Tony just looked at him for a long, quiet moment with a soft expression, then leaned forward and kissed his forehead.

"More than anything," he agreed.


	2. Chapter 2

**Summary for the Chapter:**

> "I'm going to be perfectly honest, here, I never could have predicted this," Helen admitted.
> 
> "Join the club- Peter, baby, sit still-"

**Notes for the Chapter:**

> *announcer voice* AND NOW, THE MOMENT YOU HAVE ALL BEEN WAITING FOR---
> 
> ~ba....by.... stark, do do do do do, baby stark, do do do do do~

Tony frowned, checking his watch once more just to make sure he hadn't read it wrong, but he definitely hadn't: it really did say 7:30. Which meant that if Peter slept literally another minute longer, he was going to be late for school. The kid wasn't exactly a morning person, but it wasn't like him to sleep in this late.

Panic gripped at Tony's heart for a moment. What if the blast from the alien tech last night had made Peter sick?

But if he was sick, FRIDAY would have said something by now. So that couldn't be it.

Tony dropped his coffee mug into the sink and headed for the hallway. It couldn't hurt to check, anyway. He knocked on Peter's door and waited, and when he didn't hear a reply he eased the door open and peered into the room.

Peter's bedroom was dim, light-blocking curtains drawn over the windows, because the spider baby's senses made him a little extra light-sensitive in the mornings, so it took Tony a minute for his eyes to adjust, but when they did his mouth dropped open in shock, and he hissed, " _Holy sh-"_

Peter was still asleep in his bed, and he looked... fine... but the part that shocked Tony was the fact that it wasn't the Peter he had said "good night" to the night before. Well, it probably was, he was wearing the same pajamas, but he _looked_ like a Peter that Tony hadn't seen in anything other than pictures for about thirteen and a half years.

Somehow, overnight, his teenager had become a toddler.

While Tony stood in the doorway trying to wrap his head around what the hell could have possibly happened in the eight hours between when Peter trudged off to bed the night before and now, the little toddler version of his son, looking entirely too tiny in the full-size bed and pajamas sized to fit a fifteen year old, started to stir, mumbling baby talk under his breath as he rolled onto his belly and scrubbed at his sleep-heavy eyes with little fists. His fuzzy, curly bedhead was _spectacularly_ adorable, and despite the fact that this may have been one of the weirdest experiences of Tony's life, bar none, he couldn't resist cooing at the achingly familiar sight of his baby boy, pouty and discombobulated after a good night's sleep.

"Hey," Tony said softly, opening the door a little further now that Peter was awake and leaning into the room. "I thought we were done with the diapers a while ago, bud."

Peter, sleepy as he might still have been, perked up immediately at the sound of Tony's voice, lifting his head and turning to look at his dad in the doorway. A big, bright smile lit up his face and he scrambled to sit up, the Star Wars t-shirt he was wearing flopping around him like a nightgown, threatening to slip off one shoulder as he lifted his arms up and made grabby-hands at Tony. "Daddy!" he squealed.

Tony's heart melted. He was a weak man, when it boiled down to it, because all it took to distract him from the fact that this entire situation was definitely not normal and possibly not a good thing was the sound of his child's voice calling his name, bright and happy and sweet as ever. He pushed the door fully open and crossed the room to the bed in a few steps, leaning down to scoop the little toddler into his arms. It was almost staggering, how familiar the weight was after so many years. Evidently, he had memorized the feeling of his baby in his arms more thoroughly than he ever realized.

"Hi, Peter Pan," Tony murmured, tucking Peter into his chest and kissing the top of his head. Peter hummed contentedly and snuggled under his chin immediately, and Tony wanted to cry a little bit, because it was all _exactly the same_. He shifted Peter back a little bit to check him over, despite the little boy's grumble of protest at being moved from his favorite snuggle spot. "You ok, bud? Feel ok?"

"Yeah," Peter said absently, almost dismissively, little hands reaching up to play with the collar of Tony's shirt, and Tony snorted a bit, because _that was very Teenage Peter of him_. A quick, passive, _"I'm fine"_ with no further details, although in this case that could have been because Toddler Peter simply didn't have the vocabulary to elaborate.

Tony opened his mouth to ask Peter something else, maybe see if he remembered anything about what had happened that led to him regressing back into his toddler body, but then Peter looked up at him with big, slightly guilty eyes, and pointed to where he had been curled up in the bed moments before. "Um."

It was then that Tony realized Peter was not wearing anything under the baggy sleep shirt he was currently drowning in, and there was a sizable damp spot on the front of it to match the one on the sheets.

"Oh, boy."

* * *

Tony called Helen Cho first, because first and foremost he wanted to make sure Peter was still as unharmed by whatever the hell had happened to him as she had claimed he was the night before. Plus, the Med-Bay served as private healthcare for SI employees and their families, which meant there was a pediatric wing, which meant she could bring an emergency supply of diapers until they figured out how long Peter was going to be a toddler and whether or not Tony would need to actually buy some.

"I'm going to be perfectly honest, here, I never could have predicted this," Helen admitted, as Tony did his best to wrestle a very energetic toddler into one of the diapers she'd brought (he forgot how _wiggly_ Peter had always been at changing times, especially once he learned how to stand up and walk away from Tony in the middle of it).

"Join the club- Peter, baby, _sit still,"_ Tony insisted, catching Peter for the umpteenth time as he tried to crawl away with only one wing of the diaper secured. Peter seemed to be under the impression that it was a hilarious game, giggling uproariously every time Tony grabbed him and set him back on the floor. It was endearing, to be sure, but Tony was also starting to remember how _constantly tired_ he had been when Peter was at this age the last time.

When he finally got the diaper securely on, Tony looked up at the doctor and realized she was trying valiantly not to laugh, her lips clamped firmly between her teeth to stifle the silent giggles shaking her shoulders. He rolled his eyes, scooping Peter into his lap and waving a hand in her direction. "Go ahead."

Helen reached up to cover her mouth, but the snort she let out was still audible. "Oh my god," she whispered, in between bursts of laughter. "I didn't know him at this age, he's _adorable_."

"He's a menace," Tony said fondly, allowing Peter to crawl out of his lap to toddle around the penthouse living room, touching everything he could reach and babbling idly to himself. "He took apart a TV remote once. Scared me half to death, I was afraid he was going to try to eat a battery."

Helen snickered. "He really is your son," she said, shaking her head.

Tony couldn't stop the smile that spread across his face at that, proud and fond all at once, because _yeah_ , he really was. He sobered quickly, though, reminding himself of the circumstances that led to this situation, and looked at Helen. "This isn't hurting him, is it? You said he was fine last night, but what if he's not now?"

Helen looked at Peter studiously, tilting her head. "He doesn't look like he's in pain," she pointed out. "And I'm sure he'd tell us if he was; he might like to keep things like that to himself as a teenager, but younger children tend to have less reservations about making their discomfort known." She shot Tony a sideways glance, smiling a little. "As I'm sure you know."

Tony certainly did. Peter in particular _knew_ he had Tony wrapped around his little finger from the very beginning, and he exploited it at every opportunity, tugging at his daddy's heartstrings with one flash of those great big Bambi eyes.

Tony was pretty sure he still did, sometimes.

"That being said," Helen continued, reaching into her bag and pulling out a portable version of the scanner she had used on Peter the night before, "better safe than sorry. I can scan him again, check the results to make sure nothing in his system is being damaged, and then we can start figuring out how to reverse it once we know whether or not time is a pressing issue for his health."

Tony nodded, silently giving his permission to check Peter again. The tricky part, admittedly, ended up being getting Peter to sit still long enough for her to do so. He was still exploring the living room, getting into everything within touching distance that looked remotely interesting.

"Peter," Tony called, holding his hands out to the little boy. "Come back over here, so Helen can give you a quick check-up, ok?"

Toddlers, he was starting to remember, were masters of selective hearing.

"Peter Pan," Tony cooed, his tone at least getting Peter to spare a glance in his direction before turning back to the book he had pulled off the bookshelf to inspect. "Come here, peanut, you can bring the book if you want."

In an act of what could very well have been baby defiance, Peter made direct eye contact with Tony, put the book back on the shelf, and toddled in the opposite direction.

Tony choked. "Oh my god, you little..." He stood up, crossing the room and scooping Peter up just before his little hands could close around the TV remote, lifting him high into the air and blowing a raspberry on his cheek as he carried him back to where Helen was sitting. "Excuse me, mister, who gave you permission to be so cheeky?" Peter just giggled, clearly pleased with himself. "Yeah, yeah, you're a little comedian, I know."

Helen stifled a laugh behind her hand as all this went on, then she pointed to the coffee table. "You can just set him down right there for now, so I can scan him," she instructed.

Tony pressed one more quick kiss to Peter's irresistibly squishy cheek, then did as he was told, lowering the toddler onto the coffee table to act as a makeshift examination table and stepping back. "There you go, Petey, you sit there for a minute so Helen can look at you."

Peter's eyes went wide as Tony moved away from him, and he lifted his hands, reaching for him. "Daddy," he whined softly, scooting in Tony's direction on the coffee table.

Tony frowned, unsure what could possibly be wrong, moving back to gently nudge Peter back into the middle of the table. "Sit still, bug, just for a minute, then you can play some more, ok?"

Being required to sit still didn't appear to be the problem, though. Peter perked up when Tony moved closer, latching on to the hem of his daddy's shirt with a tiny fist while Tony adjusted him. When Tony tried to step away again, however, to give Helen room to use her scanner, Peter whined again.

_"Daddy."_

_Oh._ Tony recognized that whine. That had been Peter's signature _Daddy, don't go away, I miss you_ whine for _years_. Tony's heart squeezed sympathetically, but he couldn't pick Peter back up, yet. The scan was important. "Daddy's right here, peanut, I'm not going anywhere. Just let Helen scan you, then I'll hold you again, alright?"

Peter didn't seem satisfied with the offered compromise, still trying to reach for Tony with both arms, leaning forward as far as he could without tipping over. "Daddy, _peas._ Up. Peas."

"Oh, god," Tony muttered, scrubbing one hand over his face weakly. "Helen, scan him fast, I can't hold up against this much longer."

Helen, to her credit, did _not_ laugh (much), adjusting the necessary settings on her scanner and running it over Peter quickly. The entire process only took about fifteen seconds, but Peter was already unhappy at the start of it, and he was getting dangerously close to fussy by the time Helen signaled that Tony could swoop in and pick him up, which he did instantly, because Peter's wobbly-lipped pout might actually be the thing that killed him someday, no matter what age Peter happened to be.

Once Peter was back in Tony's arms, Tony tilted his head to see the look on Peter's face, and despite the twinge in his heart from knowing his baby had missed him so much even though he could still see him, he couldn't help laughing a little at the miffed scowl Peter was now wearing.

 _"Daddy,"_ Peter huffed, probably trying to convey _that was not nearly fast enough_ with a single word.

Tony cooed, kissing Peter's forehead and bouncing him in his arms gently. "I know, I'm sorry, honey, but that was really important. You were so good, bub."

Peter's scowl lessened slightly. "Good?" he repeated, sounding a little hopeful.

Tony grinned, nodding. "Yeah, baby, really good," he confirmed, causing Peter's little face to break into the sweetest, most adorable baby smile.

"Peter _good_ ," Peter huffed happily, patting his own tummy in a self-satisfied manner.

"Peter the _best_ ," Tony corrected, unable to resist planting another kiss on Peter's cheek, before Helen was making a small noise in the back of her throat and turning to face him, scan results in hand.

"The scans are still saying he's fine," she reported, looking a little confused, albeit relieved. "Whatever that weapon did to regress his age, it wasn't harmful. Considering the damage that Toomes' other experiments have done, that's a little surprising, but maybe this one never got tested." She put her scanner back in her bag, and looked up at Tony. "If you don't mind me having a look at the tech, I can get a team together to start figuring out how to reverse it, but I'm not sure how long it will take. You may have a toddler for a while."

"Well, I think I can handle that," Tony pointed out, smiling at the little cuddlebug that was practically surgically attached to his shoulder. "I'll have to call his school and tell him he'll be out for a while, but this is... not exactly a hardship."

"I'd imagine not," Helen said wryly, smiling as she gathered her things and stood up. "I'll leave him with the resident baby expert, then. I'll let you know when I have something to report."

"Thanks, Helen," Tony said. She nodded and stepped into the elevator. As the doors closed, Peter lifted a little hand and waved at her, opening and closing his fingers and shaking his hand back and forth.

"Buh bye," he mumbled. Tony laughed at the adorable gesture, hefting Peter a little higher in his arms and turning to look at him. He was only wearing the diaper that Helen had brought up from the Med-Bay, seeing as there were no toddler-sized clothes anywhere to be found in the penthouse.

"So, here's what I'm thinking, tell me if you agree," Tony said conversationally, turning to walk into the kitchen to find something suitable for a toddler to eat for breakfast. "First order of business, we get some food in you." He poked Peter's belly gently to make him giggle, and was not disappointed. "We call you out sick from school, because little babies can't go to high school no matter how smart they are, it might raise some questions. Then we get you some clothes that actually fit, huh?"

Tony wasn't honestly sure how much of what he was saying was actually getting retained, with no idea if Peter's memory had reverted along with his body or if he still had his teenage brain within his toddler language and motor limitations. But Peter seemed to be agreeing with him, whether he understood him or not, nodding along somberly with every word.

Tony smiled. This was definitely going to be fun.

**Author's Note:**

> happy birthday to our favorite spider kid
> 
> writing all the video clips at the beginning of this made me extremely emo btw
> 
> find me on tumblr [@riseuplikeglitterandgold!](https://riseuplikeglitterandgold.tumblr.com/)


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